350 valve covers leaking and leaking and leaking - Hot Rod Forum : Hotrodders Bulletin Board
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Old 10-18-2012, 08:35 AM
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350 valve covers leaking and leaking and leaking

I have an early small block 350 that for the life of me I can't get the valve covers to stop leaking. I tried the cork and rubber gaskets and now I'm going to try using a rubber gasket with the steel core. The valve covers themselves are stamped and the heads have studs in them for holding the covers down. I've cleaned the surfaces on the head and valve cover a few different times, tried everything from tightening the nuts down from 45 inlb to 5 lbft. I know the heads aren't bad cuz they weren't leaking before I decided to take the valve covers off the engine a little while ago. Any suggestions on what else I should try? Should I be using a specific pattern for tightening the nuts on the studs?

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Old 10-18-2012, 12:05 PM
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350 valve covers leaking and leaking and leaking

Try again with the cork gaskets and clean everything with some acetone. Use some Indian Head compound on both the valve cover and the valve cover rail. Don't over-tighten the fasteners just snug them using a 1/4 drive ratchet and socket.
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Old 10-18-2012, 12:50 PM
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I agree with the above post this stuff has NEVER failed me. Use it to glue the gasket to the valve cover then apply another layer onto the head and gasket and install the valve cover. It should stick in place and keep everything from moving while you instll the bolts. Also should help keep the gasket in place while you get the cover bolted down.

Dont over tighten the bolts. Let the sealer setup before you snug everything down. Then only tight enough to keep them from backing off.

If it still leaks get new valve cover they are bent. If steel cover with pushed out bolt holes. Use a small socket and a hammer to bend them back the other way. Just be gentle. Several small taps will get it back in line.

This stuff always works. The best for water pumps as well.
Permatex 20539 Indian Head Gasket Shellac Compound

Hope this helps.
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Old 10-18-2012, 12:54 PM
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#1 - Make sure the covers are flat around the mounting holes, they distort over time or if overtightened.

#2 - Use spreader bars to distribute the clamping load over more area of the gasket rail. On SBC's I use them with studs and stainless steel lock nuts.

#3 - Use the steel core rubber gaskets.

I had a 350 Chevy and a 318 Dodge both with leaky steel covers, I did the 3 things above in conjunction with each other and no more leaks.
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Old 10-18-2012, 01:00 PM
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Quote:
Originally Posted by 85cjsm350 View Post
I have an early small block 350 that for the life of me I can't get the valve covers to stop leaking. I tried the cork and rubber gaskets and now I'm going to try using a rubber gasket with the steel core. The valve covers themselves are stamped and the heads have studs in them for holding the covers down. I've cleaned the surfaces on the head and valve cover a few different times, tried everything from tightening the nuts down from 45 inlb to 5 lbft. I know the heads aren't bad cuz they weren't leaking before I decided to take the valve covers off the engine a little while ago. Any suggestions on what else I should try? Should I be using a specific pattern for tightening the nuts on the studs?
Some of these old heads with the as cast gasket rail just can't be stopped because the mating surface is too uneven, rough, sometimes narrows.

The other problem is that with use and age the cover forms dimples around the hold down holes and the cover overall develops twists along the gasket rail that prevent it from evenly loading the gasket. The dimples can be worked out with a small ball peen hammer over a socket or small diameter pipe such that you can flatten them if not pooch the materail up around the hole, just a little bit. The other big thing that will help at this point are hold down tabs that spread the load over more area, <<< 1955-1961, 1968-1981 Chevrolet Corvette Valve Cover Hold Down Tab Set - Engine Mechanical - Edelbrock 55-61, 68-81 Corvette Valve Cover Hold Down Tab Set - 14067-03133273 - PartsGeek >>> You'll need two sets.

These things have a groove and ridge near the outboard side, for the first time I use them I'd put them on groove down to the cover and ridge up to see if they work without maring the gasket rail. If not turn them over.

Bogie
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Old 10-19-2012, 08:44 PM
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covers leaking?

i always put weather strip adhesive on cover then use thread through holes to hold the cork gasket in place,turn them upside down with a heavy book on them till morning, then smear a slight film of silicone on the head side and install useing spreader bars,next time you take them off rub the thin film off with your finger and reapply film and good to go again,you can do this 3-4 times before replacing gasket!!!i do this all the time to adjust solid lifters ... i hate leaks!!!!!!!
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Old 10-19-2012, 09:07 PM
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personally i would get rid of the cheap stamped valve covers and get a good pair of valve covers made from a thicker material. and use the rubber gasket gasket with a steele core . also permatex right stuff is a good gasket maker
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